1. Field of the Invention
This invention relates to a multiple cylinder hot gas engine heater head in which a plurality of tubes connect the cylinders with corresponding regenerator housings and in which each tube has a first curved portion of a shape which corresponds substantially to the shape of an involute curve and in which the tubes are juxtaposed so that constant gaps between the curved portions are obtained.
2. Description of the Prior Art
The prior art is elucidated best e.g., in U.S. Pat. No. 4,069,670. In this prior publication the first curved portions of the tubes connect a quarter circle segment manifold of a central regenerator with a quarter circle segment of an outer manifold arranged at a larger distance from a central axis and forming connection to the top of a cylinder.
The curved portions of the tubes are located substantially to follow a cone and the connections to the cylinder manifolds are established through straight tube parts parallel to the central axis.
Heater heads of this type are commonly used in hot gas engines heated by combustion of fossile fuel.
However, in case of solar heated engines it is desirable to increase the length of the curved tube portions but such increase will cause a simultaneous increase of the straight tube parts in the structure of the prior art. As the straight tube parts cannot be readily exposed to sun radiation they may increase the dead volumes as well as the weight and cost of the heater head.